Liquid rheostat.



H. W. CHENEY. LIQUID RHEOSTAT. APPLICATION rum) SEPT. 11, 1910.

993,027, Patented May 23, 1911.

2 SHEETS-SHEET 1.

H. W. CHENEY. LIQUID RHBOS'IAT. APPLICATION FILED SEPT 0, 1010.

993,027. I PatentedMay23, 1911.

9 SHEETS-SHEET 2.

UNITED STATES PATENT QFFICE.

HERBERT W. CHENEY, OF MTLWAUKEE, WISCONSIN, ASSIGNOR- T ALLIS-CHALMERSCOMPANY, .8, CORPORATION OF NEW JERSEY.

LIQUID RHEOSTAT.

993,027. Original application filed April 15, 1910,

Specification of Letters Patent.

Patented May 23, 1911.

Toall whom it may concern:

Be it known that I, HERBERT W. CH NEY,

I a citizen of the United States, residing at Milwaukee, in the countyof Milwaukee and State of Wisconsin, havev invented certain new anduseful Improvements in Liquid Rheostats, of which the following is afull, clear, and exact specification.

My invention relates to liquid rheostats.

The present application is a division of my co-pending applicationSerial No. 555,624, filed April 15, 1910.

Liquid rheostats of large size require considerable power foritheiroperation. I therefore propose to provide power-operated means foroperating the liquid rheostat, there being a number of novel featuresboth in the rheostat proper and its operating means. By reason of thesenew features, the operator has hisphysical labor materially lightenedand the size of the liquid rheostat proper is much reduced. Moreover, incase the rheostat is used for polyphase systems, its structure providesfor preventing or counter-acting any tendency toward unbalancmg.

The various novel features of my invention will be apparent from thedescription and drawings, and will be particularly pointed out in theclaims.

Figure 1 is a diagrammatic View showing my improved liquid rheostatconnected for controlling the resistance of the secondary circuit of aninduction motor; Fig. 2 is a plan view of a liquid rheostat constructedin accordance with my invention; Fig. 3 is a section on the line 3-3 ofFig. 2; and Fig.4 is a detail view taken substantially on the line 4-4of Fig. 2.

The device to be controlled is here illustrated as a three-phase motor 8having its primary supplied from a suitable source of alternatingcurrent, and its wound secondary connected to the plates of a liquidrheostat I 13 constructed in accordance with my invention. Theresistance of the rheostat is varied by adjusting the level of theliquid therein by varying the height of one or more overflow pipes orweirs 14, the liquid overflowing into a tank 15; from which it ispumped, as by a motor-driven centrifugal I pump 16, into the rheostat13. This continuous circulation of the liquid, whichis preferablyacidulated water, reduces the temperature of the rheostatand enables amuch smaller rheostat to be used for the work than could otherwise beused. The weirs 14 are operated by an air engine 17 air under pressurebeing supplied from any suitable source 18. The engine is provided withan oil lock 19, which prevents its accidental movement. If desired, theoil lock may be omitted, or a suitable dashpot or cataract may besubstituted for it. The direction and extent of the movement of the airengine are controlled by the master con.- trol lever 20.

The rheostat 13 has a casing 21, which is preferably provided with fourinteriorly projecting abutments 22, 23, 24, and 25. This casing may bemade of any desired material, concrete being especially suitable. Wateris supplied to the casing through the inlet pipe 26, which extends fromthe pump 16, enters the rheostat near the top, and passes downwardalmost to the bottom between the abutments 23 and 24. By this means muchobnoxious splashing is avoided. In the arrangement shown there are twooverflow pipes or weirs 14, these being located respectively between theabutments 22 and 23, and 24 and 25. The abutments prevent the passage ofthe liquid directly from the inlet pipe to the overflow weirs. The weirs14 are swung by links 27 from arms 28. fixed on a shaft 29, the latterbeing preferably supported in bearings 30 on the casing 21. The shaft 29is rotatable by the air engine 17, through suitable connectingmechanism. The downward movement of the weirs 14 is limited bycooperating shoulders 31 and 31 so located that the level of the waterin the casing 21 is always sufficiently high to cover the lower ends ofthe rheostat plates 32. These rheostat plates 32 are suspended from twobars 33 which extend lengthwise across the casing 21 near its top. Thebars 33 are preferably of wood or other insulating material, though theymay be of conducting material if other suitable provision is made forinsulating the plates 32 fromone another. There are four plates 32, thetwo outer plates being connected together and to one lead from thesecondary of the motor 8, and the two inner plates being connected tothe other two leads respectively. The distance between the yariousplates 32 is adjustable so that the resistances of the several phases ofthe secondary circuit of the motor may be made equal. It is evident, andis found to be the case in practice, that this equality is obtained bymaking the distance between the two inner plates less than that betweeneither inner plate and the adjacent outer plate. Thus unbalancing of thesystem is avoided. Near the top on both sides of the inner plates 32 andon the inner sides of the outer plates 32 there are mounted auxiliaryplates 34 which have horizontal port ions 35 and vertical portions 36.The vertical portions 36 increase extra proportionately the effectivesuperficial conducting area oi. the plates 32 to which they are attachedas the water level in the water rheostat approaches its upper limit, andthe horizontal portions 3? which project. from the adjacent sides of:ldJiICOIllT plates 32 overlap each other quite closely. as indicated inFig. 4, so that when the waterlevel in the rheostat reaches its upperlimit the main part of the rhcostat is in effect shortcircuited.

When the handle of the master control lever .20 is in the ofi' oruppermost position and the motor 8 is at rest, the pistons 39 and 40 ofthe air engine it and its oil lock 19 respectively are in theiruppermost position, the valves 43 and 44 of the air engine and its lockrespectively are in their middle or closed position, and the weirs 1-1-are in their lowermost or maximum resistance positions. The pump to maybe either in motion or at rest, but should be set in motion beforestarting the motor 8. To start the motor, its primary circuit is closed,as by the switch 11. Then the master control lever 20 is moved downward.This movement is communicated, through the link 56, the floating lever57, and the links 58 and 59, to the valves 43 and 44, moving said valvesin a coul'iter-clockwise direction to admit air pressure from the source18 to the space above the piston 39 of the air engine and to connect thespace below such piston to the atmosphere through the exhaust 60, and too en the valve 44 to allow oil to pass from the space below the piston40 to the space above such piston. The rate at which 1t may pass isdetermined by the extent of the opening of the valve 44; and also, ifdesired, by a screw 4t" by which the maximum rate may be set. Thepressure above the piston 39 now moves such piston and the partsconnected therewith in a downward direction, this movement beingtransmitted from the piston rod 41 through the arm 28. shaft 29, andlinks 27 to raise the weirs 14. This raises the level of the water inthe rheostat and decreases the lOSlStftilOClIl the. secondary circuit ofthe motor 8, thereby increasing the speed of the motor. The piston rod41 in its downward movement also moves downward the left hand end of thefloating lever 57, thus gradually closing the valves 43 and 44. Thedistance which the piston rod 41 must move in order to close the valves4 and 44 and stop the movement of the rod, depends upon how far themaster control lever 20 has been moved from its olt' position; for, foreach position of the control lever 20. there is a corresponding ultimateposition for the piston rod 41 and the parts operated therebv. Thus thelevel of the water in the rheostat 13 will rise to a height determinedby the position of the lever 20.

To increase the resistance of the rheostat, the lever 20 is movedupward. This movement is transmitted to the valves 43 and 44 to admitair pressure below the piston 39 and to connect the spaces on the twosides of the piston 40. The air pressure beneath the piston 39 raisessuch piston and the piston rod 41 to lower the weirs 14, thus loweringthe level of the water in the rheostat and increasing the resistance ofthe secondary circuit of the motor 8. The downward movement of the weirscontinues until either the floating lever 57 is moved to close thevalves 43 and 44 or the shoulders 31 and 31 engage.

Many modifications may be made in the. precise arrangement shown anddescribed. and all such which do not involve a dcparture from the spiritand scope of my invention I aim to cover in the following claims.

\Vhat I claim as new is:

l. A liquid rheostat for polyphase circuits, comprising a casingcontaining liquid, a plurality of plates immersed in such liquid andsubstantially in line with one another, there being one more plate thanthere are number of phases and the two outside plates being connected.

2. A liquid rheostat for three phase circuits, comprising a casingcontaining liquid, four plates dipping into such liquid and arrangedsubstantially in line, the two outer plates being connected together andarranged for connection to one lead of the three phase circuit, whilethe other plates are arranged for connection respectively to the othertwo leads of the circuit.

3. A liquid rheostat comprising a casing containing liquid, a pluralityof electrically disconnected plates dipping into the liquid in saidcasing and arranged substantially in line, and means above the level ofthe liquid for supporting said plates so that the distance betweenadjacent plates is adjustable while the angle between the plates ismaintained constant.

4. A liquid rheostat for three phase circuits, comprising a casingcontaining liquid, four plates dipping into said liquid and arrangedsubstantially in line, the two outer plates being connected together andarranged for connection'to one lead of the circuit and the other twoplates being arranged to be connected respectively to the other two perends to increase the efiective contacting surface of the plates, theprojections extending from adjacent sides of adjacent platesoverlapping, and means for varying the distance which said plates dip inthe liquid of the rheostat. I s

6. In a liquid rheostat, a casing containing liquid, a plurality ofplates dipping into said liquid, said plates being provided-withprojections toward their upper 'ends to increase the effectivecontacting. surface of the plates, and means for varying the distancewhich saidplates dip in the liquid of the 'rheostat.

7. In a liquid rheostat, a casing containing liquid, a plurality ofplates dipping into said liquid, said plates being provided near theirupper ends with horizontal fiat projecting portions which extend towardthe adjacent plates and overlap similar projecting portions from suchadjacent plates, and means for varying the height of said .platesrelatively to the level of the liquid in thev rheostat.

8. In combination, a casing for a liquid rheostat, a plurality ofelectrodes within the casing, a plurality of overflow weirs, means foradjusting the vertical height of said weirs, and means for supplyingliquid to the casing.

9. In combination, a casing for a liquid rheostat, a plurality ofelectrodes within the casing, an inlet pipe through which liquid may besupplied to the casing, a discharge conduit, and an abutment projectingbetween the inlet pipe and the discharge conduit.

10. In combination, a casing for a liquid rheostat, a plurality ofelectrodes within the casing, an inlet pipe through which liquid may besupplied to the casing, two discharge conduits located respectively onopposite sides of the inlet pipe, and an abutment from the casingbetween the inlet pipe and each discharge conduit. q 11. In a liquidrheostat, a casing containing liquid, a plurality of electricallydisconnected plates arranged substantially in line, said plates beingprovided toward their upper ends with projections which extend towardadjacent plates to decrease the .effective distance between adjacentplates as the plates dip farther into the liquid of the rheostat, andmeans for varying the distance which said plates dip in the liquid inthe rheostat.

Milwaukee, Wis., Aug. 17, 1910. In testimony whereof I afiix mysignature, in the presence of two witnesses.

HERBERT W. CHENEY.

Witnesses: Crms. L. BYRON JOHN L. JOHNSON.

